Several design considerations apply in respect to support means for highway guardrails. These considerations include safety and structural soundness, installability, and compliance with the applicable standards especially those of the Federal Highway Administration (FHWA). Within those criteria, a variety of designs are found in the prior art. Guardrails can be supported using a two-piece arrangement of a post with an offset block attached to the post. The guardrail-would be bolted to the offset block in this prior art arrangement. There are versions of offset blocks made of plastic, recycled rubber and composites, and wood. The present invention is an advance over the prior art, which had problems with a two-piece design and the installation problems of multiple parts, with how to anchor or drive the post into the roadside area, and with the unit cost and installation costs for a two-piece design.
Highway guardrails may be bolted to an offset block that is attached to a wooden post or a metal I-beam that is driven in the ground. That involves driving the post, delivering an offset block and hardware at each post along the highway, then joining those parts, then delivering the guardrails and hardware along the line of posts, then bolting the rails to the offset blocks. The present invention eliminates the separate offset block, and the associated joining and hardware, but it provides the lateral offset distance between the guardrail and the post that is desired.
A standard that is applied to guardrails to be used on the highways was set out in National Cooperative Highway Research Program (NCHRP) Report 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features, for the Federal Highway Administration. It deals with crash test protocols used to test any design that may be offered, and it does not set a standard for the guardrail support beams and hardware.
It is desirable to have the location where the post is driven into the roadside to be set back from the guardrail, because experience has shown that the guardrail is more effective if the wheel of a vehicle does not strike the base of the support post.